Method of distillation



l 4 March 29, 1927. J. s. MORGAN ,622,96

METHOD OF DISTILLATION Filed Jan. 30. 1923 M; Pfff/ra Z L 1w f VAFDUHS F1954 VY 4 6 mmf aus #www Patented Mar. 29,1927.

' UNITED STATES PATENT OFFICE.

JOHN STANLEY MORGAN, F LONDON, ENGLAND, ASSIGNOR TO THERMAL INDUSTRIAL AND CHEMICAL `('.l `I. C.) RESEARCH COMPANY LIMITED, OF LONDON, ENGLAND.

AMETHOD 0F DISTILLATION.

Application led January 30, 1923, Serial No. 615,963, and Ain Great Britain November 13, 1922.

purpose of separating the constituents more or less completely.

According to this invention, the liquid mixture is first distilled toobtain a suitable lower boiling fraction, the residue is then distilled with superheated steam, and the mixture of steam and vapor is cooled to a temperature adapted to condense the vapor alone; the steam, separated from the condensed vapor, -is then passed through the lower boiling fraction of the first distillation,-to vaporize aportion of this fraction; and the mixture ofv steam and vapor may then be treated to condense the vapor. During the distillation ofthe higher boiling residue with superheated steam, the lower boiling fraction may have been in the mean` time subjected to a distillation to produce avfurther fractionwhich may then receive thel steam as aforesaid. The steam may be reheated and used again as often as may be desired, vand 'may finally be condensed under such Aconditions that its latent heat serves to.

preheat liquid to be distilled. o

The process is, of course, 4facilitated 1f the several portions of the mixture are kept at al temperature about the boiling point of the constituent of highest boilingspoint among the lconstituents to be distilled.

vThe process vis most conveniently conducted at ordinary atmospheric pressure, but may be applied at suitable pressures higher or lower'than this.

The'process is particularly suitable for the distillation'of coal tar in a manner-which may be described as follows Tar is pumped through a series of heat interchangers which on the one vhand heat the tar and on the other condense the various fractions as they leave the distilling Zone. At the end of this interchange the tar is genf erally at such a high temperature that water and light spirit will in many cases have been entirely removed.A The tar thus dehydrated is then heated, such as by being pumped u nder a bath of molten lead, to a temperature at which the remaining volatile substances, with the exception of the anthracene, are vaporized. f

The pitch and anthracene are then broken up into a spray by means of a jet of super,- lieated steam, which removes the anthracene completely. The mixed vapours are led into a condenser where the antliracene only is condensed, givingup its latent heat to the previously pre-heated tar. The uncondensed steam is led out of the-condenser which is preferably reflux in type and is caused to mix with the volatiles which are given off by thel action of the lead bath or 'other Asource of heat. These vapours in the case 'of tar are often known as light oil and heavy loil or light and heavy creosotes. They, together with the steam, are led into a refiux condensing column and it is so arranged that the vapours leaving the' top will consist of light oil--and steam While the heavy oil will run back down the column and be discharged at the base. The temperature in the column may be controlled by a jacket of preheated tar.

The light oil and the re-used steamare now'conde'nsed by the cold incoming tarwhich will beraised very considerably in .temperature'by this means and ifl sufiicient steam is used the tar will have been dehydrated vat this point. A

The foregoing-will be rendered still more clear by the following description of the accompanying drawings, in which:

Fig. 1 is a diagrammatic representation of a suitable plant for the distillation' of?.l

tar,and t Fig. 2 is a detail view of a plant shown in Fig. 1.

Referring to Fig. 1, a'is a lead bath still. A pump b draws wet tar from a tank'c and forces it through pipe d into the jacket of a reflux condenser c where it becomes heated sufficiently to vaporize its water and light oils; the latter are separated from it in a vessel. f into which it flows by Way of Vipe g; the separated vapour's pass by pipe to a condenser h. The tar thus dehydrated is withdrawn' by pump i from the vessel f and is .forwarded to the still a. This is 'kept at a temperature which expels all volatile'c'onstituents, except the anthracene oil, into the refiux' condenser e (shown in'vertical section in Fig. 2). The residue from the still flows by pipe lc to an injector operated by steam admitted at 7c" from a superheater (not shown).f. The steam atomizes the residue in the tower l, vaporizing the anthracene oil and leaving a pitch to flow away by pipe l. Themixture of steam and vapour leaves the 4tower by pipe Z2 and fiows through a worm ,part of the loo r va our is largely in the vessel The temperature here is such that the anthracene oil is condensed and is separatedefrom the steam in trap m. The steam is carried by pipe n into the inner chamber of the reflux condenser e where it mixes with the oils which are condensing. These oils are chiefly creosotes and are separated b the steam into a heavy oil which leaves t e condenser by pipe o and a middle oil which passes as vapour, together with the steam, through pipe p, both `being*condensed in a condenser g through which the wet tar passes on its way to the jacket of condenser e. In this manner the heat in the steam and recovered. rude minera oil may be fractionated on similar lines.

Having thus fully described the nature of the said invention and the best means I know of carrying the same into practical effeet, I claim 1. A method of fractionally distilling a liquid mixture containing; more than two constituents, which consists in distilling from the mixture and condensing alower boiling fraction, passing superheated steam through the higher boiling fraction remaining, cooling the mixture of steam and vapor which leaves the liquid mixture to a temperature adapted to condense the vapor, and then assing the steam through the con dense lower boiling fraction to thereby vaporize a portion of the latter 2. A method of fractionally distilling a liquid mixture containing more than two constituents, which consists in distilling from the mixture and condensinga lower boiling fraction, passing superheated steam through the higher boiling fraction remaining, cooling the mixture of steam and vapor which leaves the liquidmixture to a temperature adapted to condense the vapor, then assing the steam through the con densed) lower boiling fraction to vaporize a fraction of the latter, and finally condensing the steam and pre-heating by the latent heat of condensation and the liquid mixture which is to be distilled.

3.` A method of fractionally distilling coal tar, which consists in preheating the tar to a temperature adapted to vaporize water and light oils and condensing the vapors evolved, heating the preheated tar to a temperature adapted to vaporize the middle and heavy oils and leave a residue lcomprising anthracene and pitch and condensing the vapors ot the middle and heavy oils, treating the said residue with steam at a temperature adapted to vaporize the anthracene, condensing the anthracene from the mixture of vapor and steam, bringing the steam which remains into contact with the condensed mixture of middle and heavy oils to vaporize the middle oils, and condensin the mixture of steam and vapor of the middle oils.

4. A method of fractionally distilling coal tar, which consists in pre-heating the tar to a temperature adapted to vaporizc water and light oils and condensing the vapors evolved, heating the preheated tar to a remperature adapted to vaporize the middle and heavy oils andleave a residue comprising anthracene and pitch and condensing the vapors of the middle and heavy oils, treating the said residue with steam at a ternperature adapted to vaporize the anthracene,

condensing the anthracene from the mixture of vapor and steam, bringing the steam which remains into contact with the con densed mixture of middle and heavy oils to vaporize the middle oils, condensing the mixture of steam and vapor of the middle oils, and preheating the tar which is to be treated by means of the latent heat evolved during the three last-named condensations.

In testimony whereof I have,signed my name to this specification.

JOHN STANLEY MORGAN. 

